我正在为我的用户创建操作编写一个测试，其中包括向Kafka发送一条消息。我应该在测试这一部分时嘲笑Kafka吗？最佳实践是什么？
另外，如果我想测试Kafka而不模拟它，它通常在userKafkaProducer中自动连接kafkaTemplate，但当我在测试中运行它时，kafkaTemplate为null。我该怎么办？

@Test
    public void testCreateUserSuccess() throws UserNameExistException {
        
        UserRepository userRepo = mock(UserRepository.class);
        UserKafkaProducer userKafkaProducer = mock(UserKafkaProducer.class);
        UserServiceImpl userService = new UserServiceImpl(userRepo, userKafkaProducer);

        UserDTO userDTO = new UserDTO();
        userDTO.setUserName("test_user");

        when(userRepo.existsByUserName(userDTO.getUserName())).thenReturn(false);

        User savedUser = new User();
        savedUser.setUserName("test_user");
        savedUser.setId("1");
        when(userRepo.save(any(User.class))).thenReturn(savedUser);

        User user = userService.createUser(userDTO);

        assertNotNull(user);
        assertNotNull(user.getId());
        assertEquals(userDTO.getUserName(), user.getUserName());
        verify(userRepo, times(1)).existsByUserName(userDTO.getUserName());
        verify(userRepo, times(1)).save(any(User.class));
        // Mocking the sendMessage method of UserKafkaProducer
        //doNothing().when(userKafkaProducer).sendMessage(any(User.class));
        verify(userKafkaProducer, times(1)).sendMessage(user); //mock ?

    }

Kafka生产者类

@Service
@AllArgsConstructor

public class UserKafkaProducer {

private final static Logger LOGGER = LoggerFactory.getLogger(UserKafkaProducer.class);

private KafkaTemplate<String, User> kafkaTemplate;

public void sendMessage(User user) {
    Message<User> message = MessageBuilder
            .withPayload(user)
            .setHeader(KafkaHeaders.TOPIC, KafkaTopicConfig.MOVIE_SERVICE_USER_TOPIC_NAME)
            .build();
    LOGGER.info(String.format("Kafka message sent %s", message));
    kafkaTemplate.send(message);
}
}